1. Field of the Invention
The present invention relates to a vehicle antitheft device performing an authentication processing through radio communication between a portable unit and an onboard unit and enabling the starting of a vehicle upon fulfillment of authentication, and more particularly to a remedial means for starting the vehicle when the portable unit runs out of electric charge, breaks down, or goes astray.
2. Description of the Related Art
Conventionally, there is a vehicle antitheft device performing an authentication processing through radio communication between a portable unit carried by a driver and an onboard unit installed in a vehicle and permitting the vehicle to start upon fulfillment of authentication (e.g., as disclosed in JP 2001-206199 A).
In the case of a vehicle antitheft device as mentioned above, if a portable unit becomes unusable by, for example, running out of electric charge, breaking down, or going astray, the vehicle concerned cannot be started. As a countermeasure against such a case, there is a vehicle antitheft device including the following remedial means. If a portable unit becomes unusable, an emergency password mode is entered by connecting an emergency coupler attached to the vehicle to a predetermined wiring in the vehicle. Then, a user enters a password of a predetermined digit number through switch entry from the vehicle. If the password coincides with a preset one, it is possible to start an engine of the vehicle.
However, in spite of the intention to enhance security as a vehicle antitheft device, this remedial means, which allows a password entry mode to be entered by simply connecting the coupler when the portable unit cannot be used, causes a deterioration in security. In some conventional cases as well, the coupler is stored in a box locked by a mechanical key mechanism. However, since the box can be pried open by, for example, destroying the mechanical key mechanism, it is possible to connect the coupler and induce a password entry mode.